I rarely need this salt as I lean towards sluggishness of my system but sometimes I over hydrate myself in a detoxifying flush and can't turn off the waterworks. The difference with this salt from Calc Phos is everything physical seems in order but you feel drained. Drinking fluids only aggravates the symptoms. Salts are needed to retain fluids and absorb nutrients property. Note this is not the same feeling as lethargic which is a form of sluggishness and requires another remedy. I'm from the old school of homeopathy. Unless you really get no relief and suffer "chronic symptoms" the other category is "acute symptoms" which are attacks of sort like headaches from which treatment can bring relief immediately if not permanently. Therefore, I take 6 tablets every 15min or at intervals of attack until symptoms subside.